Theology: If you have not read The Da Vinci Code, then you may feel somewhat outnumbered. Sit in any airport lounge, travel in any train carriage, laze on any beach, and Dan Brown's name seems to be on every second book spine.
He regularly occupies three slots in the top five paperbacks list; topping it with The Da Vinci Code, which has sold eight million copies in a little over two years. A modern-day murder mystery based on an ancient religious conspiracy of shadowy orders, the Holy Grail, and revelations about Christ's personal life, it has become the publishing phenomenon of the decade.
If you haven't read it, what you need to know is that the most important words come before the story even begins: "All descriptions of artwork, architecture, documents, and secret rituals in this novel are accurate." That sentence has spawned a cottage industry of books about the book; titles such as The Da Vinci Code Decoded, The Secrets of The Da Vinci Code, and The Truth Behind The Da Vinci Code. DVDs, TV programmes and websites examine its accuracy. All because the first thing most readers want to know as they turn its final page is just how much of it is actually true. Was Jesus really married to Mary Magdalene? Did they have a child? Is there a protected bloodline till this day? They look at Da Vinci's Last Supper to see if that really is, as a character claims, a woman seated to Jesus's right. They squint at the computer screen. It sort of looks like a woman . . . It could be a woman . . . At the very least, it's a pretty-looking man.
The cover of Truth and Fiction in the Da Vinci Code features that detail from the painting, but that is somewhat misleading because Bart D Ehrman is as uninterested in Da Vinci as he is in the Priory of Sion, codes in Scottish chapels, Opus Dei or any of the conspiracy's tributaries. His business is with the source. Ehrman is a historian at the University of North Carolina ("the buckle of the Bible Belt") but he avoids ministration. Instead he focuses on what history tells us about the origin of the gospels, about Jesus, Mary Magdalene and the Roman emperor, Constantine, whom The Da Vinci Code blames for de- feminising the early church and suppressing the truth about Jesus's humanity.
Okay, admits Ehrman, so it's not quite as titillating as a conspiracy thriller laced with danger and a steady drip-feed of revelation, but this stuff is worth knowing. Otherwise, public knowledge of Jesus is a mess of half-truths and hearsay. So he uses the various claims of The Da Vinci Code as an opportunity to write a primer on the early Christian church, and if it is not a page-turner to match Brown's, it is written in a clear, unfussy style that is always keen to get to the point.
He takes on and debunks several of the novel's theories and their supposed sources. The four gospels, he explains, were not chosen by Constantine in order to eradicate records of Jesus's humanity, nor can he be blamed for sidelining women in the church. There were not 80 gospels vying for a spot in the New Testament ("This makes it sound like there was a contest, entered by mail . . . "). They generally depicted Jesus as more divine than those that made the cut, not more human as Brown's characters declare. There were not thousands of followers keeping written diaries of Jesus's life, and nobody can be certain of his marital status.
Ehrman describes how the centuries after Jesus's death were marked by prolonged jostling between various sects to determine the approved canon. He examines some of the alternative gospels, and here we get a glimpse of stories as fantastic as anything Brown could imagine. The Infancy Gospel of Thomas, for instance, depicts the young Jesus as a testy little kid with the unwelcome habit of smiting other children dead or prematurely ageing them, until Joseph - understandably aghast - begs of Mary: "Do not let him go outside: anyone who makes him angry dies."
All of which, insists Ehrman, Brown could have found out if he had spent a few more hours researching the topic. Ehrman too often protests that he enjoyed the thrills in The Da Vinci Code but not the history, as if knowing he'll be seen as a bit of a spoilsport. Which he is, of course. But if you've read the fiction and would rather have the facts, there are worse places to start than here.
Shane Hegarty is an Irish Times journalist
Truth and Fiction in The Da Vinci Code: A Historian Reveals What We Really Know About Jesus, Mary Magdalene, and Constantine By Bart D Ehrman Oxford University Press, 207pp. £11.99
